1. Technical Field
The present invention relates in general to data processing systems and, more particularly, to object oriented knowledge based systems. More specifically, the present invention relates to a method of using a single object to represent multiple instances of similar entities within an object oriented system.
2. Description of the Related Art
Typically, in an object oriented system, similar entities are defined by an object class and the entities themselves are represented by object instances of the class. In some cases, the number of object instances may be large and the differences between the object instances as represented by slot values, may be small. The large number of object instances may prevent the object oriented system designer from specifying all the object instances even though the knowledge domain of all instances is known, requiring the object instances to be created as referenced.
FIG. 1 illustrates the hierarchy of a typical object class-instance arrangement. In block 1 is a class object having attributes represented by slot one and slot two. Slot one represents an attribute which has a common value for all instances of the class; therefore, the slot and value are defined in the class, but the value of this attribute is unique to each instance; therefore, the slot is defined in the class object, but the slot values are defined in the instance objects. The instance objects defined from the class object 1 are shown in blocks 3, 5, and 7. Block 3 is an instance object one where slot one has an inherited slot and an inherited value from the object class, while slot two has an inherited slot and a unique instance value. Likewise, for instance object two and instance object n in blocks 5 and 7, respectively, they too, in slot one, have an inherited slot and value from the object class, whereas in slot two they further have a unique instance value.
Unfortunately, the above approach requires at least n instance objects and adequate storage space for all n instance objects, even though there are few differences between each of the n objects. Accordingly, what is needed is a method for using a single object to represent multiple instances of very similar entities.